Process of preparing nitroxy alkyl nitramines



Patented May 18, 1954 UNITED STATES OFFICE] PROCESS OF PREPARING NITROXY "ALKYII; NITRAMINES Alfred T. Blomquist and Fred '1. Fiedorelnlthaca;

N. Y.,,assignors to the United StatesvofiAmere-- ica as represented by the Secretary ofthe N-avy No Drawing: Application December 30, 1944, SerialNo. 570,804

11 Claims;

The. present .invention. relates to nitramines and-.more particularly toanew and improved These. four nitramines are all considerably more,

powerful than 'INT, with ballistic strengths ranging from about 1.3 to aboutlb times that of TNT. Furthermore, the last mentioned com pound in this group, i. .e., DINA, isan essentially non-volatile compound that is capable of plasticizing nitrocellulose; Itis therefore of interest as .a replacement for the relatively volatile nitroglycerine heretofore used in propellants of the double base type.

Because of the increasingimportance of this class ofcompounds as a Whole, new methods of cerned consists of nitramines that contain one or more nitroryalkyl groupsin addition to a nitramino group, and which possess the char acte-ristic structure:

Nitroxyalkyl NO2N Where Y is either a nitroxyalkyl group, oran,

alkylgroup (either alicyclicor cyclic), or a substitntedalizyl gr0up.- A typical example of his type if: nitramineisthe-previously mentioned.

his (-2nitro ;yethyl nitramine (DINA) lleretofore DINA-constituted the only'jknotvn:

The provision of a greatly im 21 example-01a nitramine containingyainitroxyalkyla group and for this reason the preparation. of: DINA. .will: serve to illustrate the f difiic-ulties-.- encountered the preparation: ofca compound. of.

'- this general type by-the prior art -methods.-

Asdeseribed and claimed in the copendingaprplicationsof Wright and Chute; Serial No. 570 ,-81 i, i now- Patent 2,462,052, and (Jason; SeriahNo. 570,811, both filed of even date herewith, DINA has heretofore -been& prepared from diethanolamine by the following, series 'of oreactions, the. second of which is-rcatalyzed: by chloride. or... bromideeion forming material;

Two modifications: :of this basic procedure have: been proposed :bytWright and1Chute.-.. 'lheriirst or one=sta'ge. modification involves the: .trea-t-- merit of the appropriate secondary amine (diethanolamine) with" anequivalent amount '(3 moles): of nitric: acid-and: an: equivalentvamount. (3 Jmoles): of acetic anhydride 1 the presencee of a halider-iont-forming catalyst? such as a rchloride.-. The second. or: twoestage modification, involves the initial conversion hither-appropriate r amine-s (diethanolaminelto the. corresponding bis nitroxyalkyl amine'nitrate-after which the: isolated salt isntreated-eima second stage reaction with acetic anhydride in? the :presence of anappropriate catalyst.

Neither. of. these smodifications proved to be entirelysatisiactoryr for large-scale manufac turing operations. Ontheonethand, the-onestage' modification was somewhatdifilcult to regulate. thermally because.- of the. .large=amount of heat evolved fromthe-two .reactionstaking place in the reaction mixture- Furthermore. it has i, been found that-certain. alkanolamines .tendltd inflame whentadded tola .mixtureofthe. nitric. acid, the anhydride and-the catalyst. Th'etwo stage modification,. on the other. hand, though more satisfactory from the point offview of temperature regulation, required the. use of. a .very...

large excess of substantially, anhydrous.v nitric acid inorderto "convert the diethanolaminewtoi the bismitroxyethyl).*amine nitrate. In. is01at ing;.this-.salt,-.thisz large excess of nitricsacid..was.

-- wasted,- inasmuch as isolation involved the drown-- ing of the reaction mixture in a large volume of ice Water. Thus Wright and Chute in application Serial No. 570,814, now Patent 2,462,052, employed 60 moles of 99-100% nitric acid to convert 4 moles of diethanolamine to the bis(nitroxyethyDamine nitrate. This corresponds to five times the equivalent amount of nitric acid theoretically required. The reaction mixture resulting from this treatment was then poured into 6 kg. of ice water. It will therefore be apparent that the two-stage modification, while more satisfactory from the viewpoint of temperature control, involves the loss of a very large proportion of anhydrous nitric acid and also requires the isolation and handling of a solid prior to the second stage of the process.

Broadly speaking, the object of the present invention is to provide a new and improved method of converting a secondary amine having one or more alkanol groups, to the corresponding nitramine containing one or more nitroxyalkyl groups.

A more particular object is to improve the ease of thermal regulation and at the same time to minimize the nitric acid consumption in the conversion of certain secondary amines containing one or more alkanol groups to the corresponding nitramines having one or more nitroxyalkyl groups.

Still further objects are to avoid the hazard created by the tendency of certain secondary alkanolamines to inflame when contacted with a mixture of anhydrous nitric acid and acetic anhydride containing a bromide or chloride catalyst; and to provide an improved procedure that is more readily adaptable to large scale manufacture in either a batch or continuous type of operation.

Other objects and advantages will be apparent as the invention is hereinafter more fully described.

The foregoing objects may be accomplished by the two-stage process of the present invention which is applicable to those secondary amines containing one or more alkanol groups, that are capable of forming a normally liquid mixture when mixed with approximately the theoretically equivalent amount of substantially anhydrous nitric acid. In the first stage of the process, the selected secondary amine containing one or more alkanol groups is merely mixed with approximately the equivalent amount of substantially anhydrous nitric acid to form a liquid mixture. The heat liberated during mixing is readily removed, for which reason thermal regulation of this and the subsequent stage of the process is a relatively simple matter.

The first stage reaction mixture probably con tains the amine nitrate salt but the hydroxyl groups in the indicated class of alkanolamines apparently are not completely esterified. It is perhaps for this reason that the amine nitrate salt of the indicated class of alkanolamines remains in solution in approximately a theoretically equivalent amount of nitric acid. In any event, regardless of the explanation, the first stage reaction mixture consists of a liquid, and it is therefore readily adaptable to being continuously fed to the reaction system wherein the second stage of the process is to be carried out.

The second stage of the process is effected by bringing the liquid firststage reaction mixture into reactive relation with an approximately equivalent amount or" a dehydrating acid anhydride, in the presence of an appropriate halideion-forming catalyst, at the selected reaction temperature, preferably between about 5 C. and about C. Thereafter the second stage reaction mixture is diluted with water and the resulting precipitate is separated from the mother liquor.

In carrying out the first stage of the process a large excess of nitric acid is not necessary. Indeed we prefer to use roughly from 1 to 1.2 equivalents of nitric acid per mole of amine undergoing treatment. If the starting material contains but one secondary amine nitrogen and but one hydroxyl group, two moles of nitric acid per mole of amine is of course one equivalent of nitric acid. If the starting material contains either two hydroxyl groups and one secondary amine nitrogen group, or one hydroxyl and two secondary amine nitrogens, then three moles of nitric acid per mole of the starting amine is one equivalent of nitric acid. The computation of the equivalent amount of nitric acid is therefore a relatively simple matter and in carrying out the first stage of the process, the theoretically equivalent amount of nitric acid s preferably increased somewhat by multiplying the theoretical amount by a factor of 1 to about 1.2. Thus the nitric acid consumption is reduced by a factor of almost five and at the same time optimum yields are obtained. In short, the use of more than about 1-1.2 equivalents of nitric acid per mole of amine is unnecessary and any amount in excess of 1-l.2 equivalents is to be regarded as surplusage.

The temperature during the first and second stages of the process may be varied within wide limits. ihe first stage may be carried out between about 5 C. and about 50 (1., the lower limit depending partly upon the solubility of the amine salt in nitric acid, and the upper limit depending largely upon safety considerations. Preferably the first stage is carried out between about 10 C. and about room temperature or slightly thereabove. During the second stage the reaction may be effected between about 5 C. and about 65 C. or above, optimum yields generally being obtained at a reaction temperature roughly between about 30 C. and about 45 C.

In carrying out the first and second stages of the process, it is immaterial whether the reaction components are simultaneously introduced into the reaction vessel, or introduced successively. In small scale runs, the addition of one component to a vessel containing the remaining component or components is usually more convenient while in large scale runs simultaneous addition may be preferable.

The catalyst employed during the second stage may consist of any of the chloride-ion or bromideion forming materials described in Wright and Chute, application Serial No. 570,814, now Patent 2,462,052, and in the above mentioned Cason application. We prefer, however, to use the chloride-ion-forming catalysts such as hydrogen chloride, metal chlorides, amine hydrochlorides, or fatty acid chlorides such as acetyl chloride, the latter being especially convenient for laboratoryscale preparations because of its liquid condition.

Generally speaking, the process of the present invention is applicable to those secondary amines containing one or more alkanol groups, that dissolve in an approximately equivalent amount of substantially anhydrous nitric acid to form a normally liquid mixture. As illustrative members of this class of starting materials, the following may be mentioned: diethanolamine, ethanolmethylamine, ethanolethylamine, ethanol '5. butylamines: isopropanolmethylaminasandiithe like:

- Crtainrof.theiprodxictsobtained byitheprocess" of the present inventibnr-aremore-particularly describediand claimed as.newcompounds.in one.

or'more of thefollowingcopending patent applications, all of which are filed of even date here'- with: Wright and Chute application Serial No. 570,813,: now Patent 2,461,582'jand Blomquist and Fi'edorek application Serial No. 570,805, new Patent 2,481,283.

Inorder more clearly to disclose-the nature of the present invention, severalv specific examples; will'hereinaiter bedescribed in considerable-dd tail.'.- It is to be. clearly understoodihowever, that! this is done solely'by way -of illustrationand not forthe-purpose of delineating the breadth of the present invention or of restricting thearnbit of the. app ended claims;

Erample L -T zho-stage' liquid-feed preparation H ployedthrough the-addition of a theamine-to the XVII nitric acid (note 3) The solution (154.1 g.) of diethanolamine int:

nitric acid was transferred to a dropping funnel and added dropwise to a solution oi..0.86...g., (0.011

mole) of acetylchloride. (note 4) and .177. g. (1.73

moles) of acetic anhydride (note:'5)""contained in' a 500* cc;; three-necked flask. Stirring was employed *throughout the '1 addition; which. required fifteemminutes; and the temperature was maintained at "35 "C;' by" means of intermittent coolir'igwith: an'ice and water bath. The reaction mixture'washeld-at35 C. for'fifte'en minutes after addition of the reactants was completed and thentz-poured into: 12.00 sec: on: ice --and: :waterz.

determination .on-utheva nitric acid used showed presence of approximately 0.65% .HNOa.

2.1: At. temperature-below 10 Ci 1 crystalsof.v a solid tend to separate from .thevdiethanolaniine-e nitric. acid-.solutionwhen nearingthe; theoretical. ratio of-the reactants..-. Upon-3 warming up; to. 205 the solid dissolves-rapidly;

3.: Forazaaseriesrof comparative runs -it:is ..con-..- venientito preparefa iargenquantity ofldiethanol'r amine-nitric acid solution and use weighedpon tions'.: This: -can: be:-= prepared: conveniently by adding concurrently andrsimultaneously the. pro-.;

portionatek-amountstoia diethanolaminee and:98.%1: nitric-acid .to la small. batclfiofimixture*previously prepared separately. A .reaction temperature of C., maintained.by' externalcooling, is satisfactory.

4.-. For catalyst trials the substanceto be tested. was introduced insteadoiacetyl chloride, 111501111 tion or suspensionm the acetic anhydride.

5.- Baker and Adamson acetic anhydridewhich was assayed as .a100%i A020 by'jtitration"with: standard alkali was used. This .material.was.= labelledi95-% acetic anhydride.

(1) Optimum temperature-A i series. 01 ex periments to determine the effect of temperature on the-yield and quality. of DINA produced by "the foregoing. procedure disclosed. that maximum ayieldsand higher qualityof DINA were obtained at operating temperatures in the range 35-i5 At higher or lower temperatures the yields diminishedmarkedly and the quality of the DINA,'. as-observed from the melting point of the prodnot, was somewhat. inferior.

, chloride.

TABLE .I.INFLUENCE 'OF TEMPERATURES IN THE CONVERSION- OFDEA-HNOa SOLUTION. TO DINA.

Temp. DINA Yields i P'." (p c nt) 5 14.0 12 48-49 15 60: s to: 485549. 5 98:2 82 50-51 114.7 9e 50.5-51.6 113. 9 95 49-50 73. 2 61- 46: 5-48.15

1 Procedure described above was employed. The diethanolamine? was ohtalned from Carbide and. Carbon Chemicals Corporation; and'was usedewithout further purification.

(2) Cdtalysts inihe preparation--01 DINA.'A preliminarysurveyof possible catalysts is shown in Table II. Wright and Chute (application Ser. No: 570,814, new Patent 2,462,052, filed of even date herewith) have demonstrated the catalytic action .of various chlorides an the conversionof i the-nitrate of bis-N,-N- (z-nitroxyethyl) amineto DINA and Cason..(application Ser. No- 570,811,. filed of even date .herewith) obtained. catalyticv effectswith'certain bromides; It has alsobeen found that hypochlorites and chlorates are efie'ctive "as catalysts: Potassium perchlorates; on. thesother -hand; was ine-lrectiva-and so was chlo roacetic%.acid.-= Sulfur monoch'lorides; acetyl chlo ridegsxandinitro'syi chloride'gave 87.6, 93.8-95.6,- and 8'Z=.7 perrccnt yields of DINA, respectively." Ammonium bromide gave a smallyield (3.0 per cent) .of DINA.andpotassiumbromate catalyzed the1.-formation'. of DINA to a slightly greater de-" gree (:6.7'per=.cent) The yields of DINA withhypochlorite -and chlorate as catalysts .at 35.--and 45C. paralleled? those with acetyl chloride at-'35* and 45 C. (of. Table II). In allcases'the yield at 45"C. was slightly less than at 35 C.

(3) Effect citations concentrations of .cata.-. Zyst.--The yield ofDINA is also subject to the. influenceofthe concentration of the catalyst as shown in Table iirelatingto experiments em-a. ploying acetyl chlorid and .in Table .IV relating to experiments employing potassium" chlorate. There is an optimum concentration at which the catalyst: is...most:' eiiectiva... The T highest'iyields. were obtained when 0.011,.1no1e of catalyst perw 0.50 moleof DEAwas usech" TABLE II.CATALYSTS FOR CONVERSION OF DEA TRINITRATE TO DINA Catalyst I DINA Yield M. P. (0.011 mole/0.5 mole) (g.) (percent) C 112. 6 93. 8 0 0 0 0 0 0 0 0 0 111. 2 92. 7 K0103 (45C.) 110. 4 92. 0 Ca(OCl)z (35 C.). 111.8 93.2 Ca(OC1)z (45 C.) 109.4 91.2 I2 0 0 8. 0 6. 7 0 0 0 0 0 0 0 0 0 0 S1011 105. 1 87. 6 19-50 Z-naphthalenesullonlc 0 acid. 1011 13401101 .1120 0 NazMoOcZHgO 0 KC-N S 0 1 Procedure described above was followed, using DEA obtained from Carbide and Carbon Chemical Corporation.

1 Where the conversion of the amine nitrate to DINA was incomplete the quenching was carried out using 2 liters of water in order to dissolve the unreacted salt.

TABLE III.YIELDS OF DINA USING VARIOUS AMOUNTS OF ACETYL CHLORIDE AT 35 C.

ACC] DINA Yield M. P. (moles) (g. (percent) C.)

TABLE IV.YIELDS OF DINA WITH VARIOUS AMOUNTS OF POTASSIURI CHLORATE, 35 0.

K0103 DIN Yield .M. P. (moles) (g.) (percent) o.)

1 Procedure described above was used, with DEA obtained from Carbide and Carbon Chemical Corporation.

TABLE V.YIELDS OF DINA WITH VARIOUS AMOUNTS OF ACETIC ANHYDRIDE 1 1 A020 DINA Yields :M. P. 2 (moles) (g.) (percent) C.)

Procedure described above was used, using 0.5 mole DEA, 1.58 moles nitric acid, 0.011 mole acetyl chloride, and various amounts of anhydridc.

2 DEA from Dow Chemical Company was used in 52-58.

8 (5) Efiect of various quantities of nitric acid- Several runs with various amounts of nitric acid in the foregoing procedure have been made. The results are given in Table VI.

TABLE VL-EFFECT or VARIATIONS IN THE EXCESS OF NITRIC ACID IN THE TWO-STAGE, LIQUID-FEED PROCEDURE 1 Nitric Acid Yield Run No.

Moles :58:5 Grams Percent l DEA from Dow Chemical Company was used in all runs.

TABLE VII.PREPARATION OF DINA BY THE TWO- STAGE, LIQUID-FEED PROCEDURE; DILUTING TO 30 PER CENT ACETIO ACID 1 Yield Run No. M. P. C.

Grams Percent DEA from Dow Chemical Co. used in all runs.

(7) Effect of varying the holding time in the preparation of DINA by the two-stage, liquidfeed procedure.-Results of several experiments in which the holding time of the foregoing DINA preparation was varied disclosed that the reaction was practically complete n 10 minutes. Lengthening the holding time improved the yield but slightly.

Ewample II.-Two-stage, liquid-feed preparation of N-(Z-nitroxyethyl) methyl nitramine (Me- NENA) CHzCHzONO? The following procedures are typical of the two-stage preparation of Me-NENA, using a mixture of nitric acid (98 per cent) and methyl ethanolamine instead of the solid dinitrate.

(1) Procedure A.--A mixture of methyl ethanolamine and nitric acid was prepared by slowly adding 37.5 g. (0.5 mole) of methyl ethanolamine to 64.5 g. (1.0 mole) of 98% nitric acid, while maintaining the temperature of the reaction below 10 C. by means of external cooling. This reaction was carried out in a 500 cc., three-necked flask, provided with a stirrer, thermometer and a capillary tipped dropping funnel, the end of which was immersed below the surface of the nitric acid. Moderate stirring was employed throughout the addition.

The mixture of methyl ethanolamine and nitric acid was transferred to another dropping funnel and added dropwise to a. solution of 3 g. (0.022 mole) of zinc chloride and 118 g. (1.1 mole) of '9 95 acetic anhydride.-contained:in--500- 00., threeneckedfiask. EStir-ring was employedrthroughout the. addition which required: fifteen minutes: and the temperaturemaintained;at 15,.C:.-loy means of intermittent: cooling in an tice-orwater, bath. After stirring for anadditional ten minutes the solution was heated-to 1'10" '0; and :kept;at .this temperature for twenty :sminutes. -a(Little.;.heat revolution occu. mat-thistemperature-When'the additionljiscarried: out :at room-.rtemperature "or higher. However, if the addition is carried out below room temperature there is considerable heatevolution. upon heating.) The reaction was quickly cooled to room temperature and then poured slowly over 550 gpof ice and water, employing vigorous stirring. A sandy precipitate of .Me-NENA- formed which was filtered offend washed with two 50 cc. portions of water. After yair drying for twenty-hounhours, it .wasdesic- .cated in vacuum-over phosphorus pentoxide for another: twentyi-four hours. :The .crude.material ("crop l) weighed. ee sit-38 39 C.

A second crop of Me-NENA can be'obtained' by neutralizing the filtrate from thefirstcrop.

'When;the above filtrate was neutralized "with.

approximately 195 g. or sodium bicarbonate; .a small amount of precipitate formed which was filtered and washed with two. 25 cc. portions of water. There was obtained 728g. of solid (crop 2) melting at37-38 C.

' The combined yield of crude Me-NENA by this procedure'was 72.4 g. or 88 percent of the:'theoretical.

(2) Procedure .B.-+Amixture of 37.5 (0.5 mole) of methyl ethanolamine and64.5"g. (1.0 mole) of 98% nitric acid was prepared employing the directionsrgiveniin procedureA.

The seccndstep in thepreparation of Me- NENA is best carried out in'a 500 00., threenecked flask fitted with stirrer, "thermometer, and dropping funnel. The mixture of methyl ethanolamine and nitric acid was added 'dropwise with stirring to .a solutionof 3 g. (0.022-mole)-of zinc chloride and. 116 g. (L1 mole) of acetic anhydride maintaining the: temperature -of the -reaction at-35 Cpby means-of intermittent cooling. The addition required lSminutesand. after it was completed, the reaction was stirred for an additional fifteen minutes at the same temperature and thenpoured over 550 g. of ice and water employing --vigorous stirring. -Me-NENA precipitatedand was filtered. After washing twice with-50 cc. portions of water the product was air dried. The final trace of moisture was removed by vacuum desiccation over phosphorus pentoxide. Thecrude product (crop 1) weighing 66.1 g. melted at 38-39 C.

(3) Procsdure'U-A mixture of methyl ethanolamine and 98% nitric acid was prepared following the directions of procedure A using in this case 37.5 g. (0.5 mole) of the amine and 67.7 g. (1.05 *moles) of acid.

The subsequent step-was carried out a 500 cc., three-necked flask, provided with-stirrer, thermometer-and dropping funnel. The aminenitric acid solution was added drcpwise to a-solution-of 1.5g. (Unit-mole) of zinc chloride in 118 g. (1.1" moles) of acetic anhydride', keeping the temperature :of the reaction at" 35 C. 1 -After 'theaddition;. which required fifteen minutes, the reaction-was stirred for an additional fifteen minutes atthensame temperature;andiimmediately poured into- 550 g.;of ice and water. Vigorous stirring was employed. .-.The precipitate.-;was "filter-admit and washed with two 50:cc.';.=pcrtions. of water with three 300'cc.'portions of water.

and. thenv allowed to;..dry.:in::air. z'lheifinalz trace of ,inoisture was 1 removed by :drying in vacuum :moles) --of.98% nitric acid. This-mixture-was prepared .as described in .proced'ureA. There s was .then added concurrently and simultaneously 187.5 g. (2.5 moles) of methyl ethanolaminefand 338.5. g.. (5.25lmoles) of. 98% itric. acid. ..The .temperature throughout the addition Waskept at 10-15" C.

The three mole mixture of, alkamine dinitrate was transferred to. a" dropping funnel and added toa s'olutionioi 768g. (6.61'1110165) 'oi aceticanhydride and 5.2g. (0.056 mole)"of acetyl chloride contained in a three-. liter-fiask. fl'li/loderatei'stir ring was employed" and the reaction maintained 24335" 'C. The addition requiredtwentyminutes. After the addition the reaction was' stirred for fifteenrminutes at the .same. temperature and then poured over'330fl cc. oIi-ice .and water. Me- NENA precipitated and was filtered'and washed There was obtained 416 g. of the substance,'*melting at 37- 38 C.

The filtrate containing the washings was neutralized with a calculated amount-of sodium carbonate. Approximately 20 g. of additional-prod uct, waswobtained. This was recrystallized vfrom ether and therewas obtained 14 gziof second crop Me-NENA, MJP. 38-39" C.

' Total yield: 86.9 per cent.

I (5) Solubz'lz'tuoj Me-NENAk-Since'Me NENA 1s 7 very. soluble in both glacial :acetic acid.- and aqueous. .acetic.-.acid.. and is slightly soluble ..-in water..(.76. g./1 00 .cc.) the isolationpfi thiss-sub stance in .the maximum possible'yield ifromsthe diluted reaction mixture :is. dependent-upon the solubility of Me-NENA in aqueous aceticsacid. Table VII, shows the solubility -of M e-ldElq A various concentrations :of 1 aqueous acetic :acid (0-50, per cent).

TABLE VIII..SOLUBILITY. oFoMc-NENA 1 n AOETIC' ACID. AT 2511. N GUS .HOAc, (percent) The maximum: precipitation of Me-NENA occurs atapproximately 20 per cent aceticacid. "Consequently,.the isolation of Me-NENA from-the reaction mixture is .preferably carried --out -by quenching themixtureawith-:sufii'cient -water" to give a 20 per cent acetic'acid's'olution.

(6) Optimum temperature in preparation of Me-NENA.A series of experiments employing theoretical quantities of methyl ethanolamine and nitric acid with a 10 per cent excess of acetic anhydride showed clearly that the optimum second-stage temperature for the preparation of Me-NENA was about 25-35 C. The results of experiments carried out at different temperatures are listed in Table IX.

TABLE IX.EFFECT F VARYING THE SECOND-STAGE 1 Procedure B of Example II was followed, employing the tempera tures indicated in the table.

Table X lists the results of experiments in which the addition of the amine-nitric acid solution to acetic anhydride was carried out at different temperatures and then allowed to remain at 40 C. for twenty minutes. The yields in all cases were fairly uniform, falling off somewhat at higher temperatures.

TABLE X.PREPARATION OF Me-NENA AT VARIOUS SECOND-STAGE TEMPERATURES FOLLOWED BY "DIGESTION AT 40 0.

(7) Influence of varying amounts of acetic anhydride in the preparation of Me-NENA.-The results of several experiments disclosed that a slight excess of acetic anhydride over the theoretical requirement (i. e., about per cent excess) gave somewhat better yields. Increasing the quantity of acetic anhydride from 1.1 mole to 1.4 mole per 0.5 mole methyl ethanolamine did not improve the recovery. The results of the experiments are given in Table XII.

TABLE XIL-VARIATION IN PROPORTION OF ACETIC ANHYDRIDE IN THE PREPARATION OF Me-NENA A010 Me-NENA Percent M. P. Run 1 (moles) Crop I (g.) Y C.)

1 Procedure B of Example II (0.5 mole run) was followed, varying only the moles of acetic anhydrlde. In isolating the product the reaction was quenched with enough ice and water to give a percent solution of acetic acid.

(8) Influence of varying amounts of nitric acid on preparation of MeNENA.-The influence of varying amounts of nitric acid is summarized in Table XIII. There is a very slight increase in the yield of Me-NENA when the amount of nitric acid is varied from 1.00 mole to 1.20 moles per 0.50 mole of methyl ethanolamine.

Adam Hddmg Me-NENA Percent M P TABLE XML-EFFECT or NITRIC ACID IN THE Run '{g gg- '{g gg r yield 0, PREPARATION or Me-NENA 5 40 58.6 71.0 37-38 40 Run N0 nno. Me-NENA Percent M. P. 15 40 e4. 3 78. 3 38-39 (moles) Crop I (g.) Y ld o. 40 64.6 78.3 37. 538.5 35 4o 33. 2 80. 3 -37. 5 40 63.4 73.9 38-39 1.00 66.1 80.1 38-39 4o 57. 3 69. 5 38-39 1.05 36. 5 80. 3 37-38 1.10 as. 7 80.8 37-38 1. 20 67. 5 81. 8 37-38 1 Procedure A of Example II was employed.

The catalyzed "dehydration reaction occurring during the second stage of the present process is subject to the influence of temperature and time, as shown in Table XI. Runs 11 and 14 (in which the holding time or digestion period was 15 and 120 minutes, respectively, at 15 C.) showed a marked difference in the yields of Me-NENA. The yield in the former was 43 per cent, whereas the yield in the latter was 68.4 per cent. At a higher temperature the reaction was completed in a relatively short time. Runs 8 and 13 showed slight variations in the yield when the holding time was 15 and 0 minutes. It is quite probable that at moderately elevated temperatures some decomposition of Me-NENA by the acid solution occurs.

TABLE XL-EFFECT OF SECOND-STAGE HOLDING TIME IN THE PREPARATION OF Me-NENA 1 Procedure B of Example II was followed subject to the variation in temperature and holding time indicated in the table.

1 Procedure B was followed.

(9) Catalysts in the preparation of Me- NENA.-It appears from an examination of Table XIV that the catalytic effect of the chloride or bromide ion is essential for the conversion of the nitrate of N-(2-nitroxyethyl)-methylamine into Me-NENA. This is borne out by runs 22 and 31. In the former no catalyst was employed; in the latter sulfuric acid was used. In each of these experiments no Me-NENA was isolated.

lhe yield of Me-NENA is also subject to the influence of the concentration of halide ion and as it is observed in Table XIV; in experiments employing zinc chloride, there is an optimum concentration at which the catalyst is most effective. The highest yield was obtained when 0.011 mole of zinc chloride per 0.50 mole of methyl ethanolamine was used.

Other chlorides, it was found, were equally as effective as zinc chloride. Acetyl chloride, aluminum chloride, ammonium chloride, sodium chloride and hydrochloric acid gave excellent yields and ferric chloride was somewhat less effective. The results also showed that potassium chlorate and sodium hypochlorite were effective catalysts while potassium dichromate and sodium sulfite were without effect.

cstatic TABLE XIV.CATALYTIC STUDIES ON MG NENA. 1

. .Exp. Catalyst Me- NENA' .Yield I. N 0. Catalyst (moles) (g.) (percent) C.)

\ O O. 0007 14. 4 17. 5 0. 0337 69. 3 $4.0 0.3011 -79. 1 35. O D. 022 66. 5 8D. 6 0. 07-: 51 6 72. 2 0. 011 71. 4 86. 5 v 0. 011 $9. 1 33. 8 (X011 70. 4 8513' 0.011 0 0 O. 011 70- 6 85. 5 0. 011 67. 9 82. 'c' 0. Q11 64. 4 78. 1. 0. 011 67. 2 5 0. 011. 5:7 6. 9 7 0.0007 0 0 NaOCL". 0.011 55. 2 67.0- N32505:.-. 0.011 0 '0 K2C1201 0. 011 0 0 PProc'edure G was used. 7 w w 1 Exp. D was run. at 15 .C. whercasthe other runs were at 30 L. Example III .-Two-stage, liquid-feed preparation of N-(Z-nitrowyethyl)ethylnitramine (Et-NENA) CHzCHgONOz NO2N CHzCHa Into a 500 cc., three-necked flask containing 67.7 g. (1.05 moles) of 98 per cent nitric acid and equipped with stirrer, thermometer and a capillary tipped dropping funnel whose end was immersed below the surface of the acid, there was added 4.4.5 g. (0.5 mole) of ethyl ethanolamine. The contents of the flask were cooled externally and the temperature maintained below 10 C. during the addition.

The amine-nitric acid mixture was transferred to a dropping funnel and added dropwise to a solution of 118 g. (1.1 moles) of 95 per cent acetic anhydride and 0.86 g. (0.011 mole) of acetyl chloride contained in a 500 cc., three-necked flask. Moderate stirring was employed and the reaction was maintained at 35 C. After the addition of the amine-nitric acid mixture which required fifteen minutes, the reaction was kept at 35 C. for an additional fifteen minutes. pouring the contents of the flask into 550 cc. of ice and water there was obtained an oil which was separated and washed successively with two 100 cc. portions of 5 per cent sodium bicarbonate and two 100 cc. portions of water. After filtering, the pale yellow oil was dried by bubbling dry air through it. There was obtained 73.4 g. (82 per cent of theoretical) of N-(2-nitroxyethyl)ethyl nitramine melting at 4-5.5 C.

D4 =1.32; n =lA79 Theoretical molecular refraction=38.75. Observed molecular refraction=38.4.

Example IV.Tw0-stage, liquid-feed preparation of N (2 nitromypropyl)methylnitramine (Mez-NENA) Into a 500 cc., three-necked flask fitted with stirrer, thermometer, and a capillary tipped dropping funnel whose end could be immersed well below the surface of the reaction mixture there was placed 67.? g. (1.05 moles) of 98 per cent nitric acid. To this there was added by means of the dropping funnel 44.5 g. (0.5 mole) of 2-hydroxypropylmethylamine. The contents of the flask were externally cooled to a temperature be- After --low 10 C. and maintained at thiscitempera- --was-maintained at 35" C. After theaddition of the amine-nitric acid mixturewhich required fifteen minutesjthe reaction was kept at 35 C. for

:an additional fifteen minutes'. After pouring the contents of. the flask into 550cc. of ice an'd water there was obtainedan oil which was separated and washed successively 'with'two ccnpor-tions of 5 per cent sodium bicarbonate and two -100- 'cc.

portions of water. Afterfiltering; the pale yellow oil was dried bybubbling dryair through it.

There was 65.8 g. (74 per cent of theoreticab 'of -N- (2-nitroxypropyl) methylnitramine .as a pale yellow oil, melting..-.at -'22-'-23-"C.

-We claim:

1. A method of preparing a nitroxyalkyl nitramine from a secondary amine of the class that (a) contains at least one alkanol group and (b) is capable of dissolving in an approximately equivalent amount of substantially anhydrous nitric acid to form a liquid reaction mixture, which method comprises mixing said secondary amine with about an equivalent proportion of substantially anhydrous nitric acid and then bringing the resulting liquid reaction mixture into reactive relation with about an equivalent proportion of a dehydrating acid anhydride in the presence of a small proportion of a halideion-forming catalyst selected from the group consisting of chlorine and bromine.

2. A method of preparing a nitroxyalkyl nitramine from a secondary amine of the class that (a) contains at least one alkanol group and (b) is capable of dissolving in an approximately equivalent proportion of substantially anhydrous nitric acid to form a liquid reaction mixture, which method comprises: mixing said secondary alkanolamine with about an equivalent proportion of substantially anhydrous nitric acid; then bringing the resulting liquid reaction mixture into reactive relation with about an equivalent proportion of a dehydrating acid anhydride in the presence of a halide-ion-forming catalyst selected from the group consisting of chlorine and bromine to form a second reaction mixture; maintaining said second reaction mixture at a temperature between about 5 C. and about 50 0.; and then separating the nitroxyalkylnitramine from said second reaction mixture.

3. The method of claim 2 wherein said first stage reaction mixture is cooled to about room temperature before being brought into reactive relation with said anhydride.

4. The method of claim 2 wherein said anhydride is a lower fatty acid anhydride.

5. The method of claim 2 wherein said anhydride is acetic anhydride.

6. The method of claim 2 wherein said secondary amine contains at least two alkanol groups.

7. In the preparation of bis(2-nitroxyethyl) nitramine, the improvement which comprises: mixing about one mole of diethanolamine with about three moles of substantially anhydrous nitric acid to form a liquid mixture; cooling said liquid mixture to a temperature above about 10 C. but below about 50 C.; bringing the resulting liquid mixture into reactive relation, at a reaction temperature between about 5 C. and about 15 60 C. and in the presence of a catalytic amount of a chloride-ion-forming catalyst, with about three moles of a lower fatty acid anhydride; mixing the resulting reaction mixture with a large proportion of water; and separating the resulting precipitate from the mother liquor.

8. The improvement of claim 7 wherein said anhydride is acetic anhydride.

9. The improvement of claim 7 wherein said catalyst is hydrogen chloride.

10. A method of preparing N-(Z-nitroxyalkyl) alkylnitramine which comprises bringing about one mole of N-(2-hydroxyalkyl)alkylamine into reactive relation with about 2 to about 2.2 moles of nitric acid to form a liquid reaction mixture; bringing said liquid mixture into reactive relation with about 1.6 to about 3 moles of a dehydrating fatty acid anhydride, in the presence of a halideion-forming catalyst selected from the group consisting of chlorine and bromine and at a reaction temperature between about 5 C. and about 60 0.; and then separating the N-(2-ni- 16 troxyalkyl) alkylnitramine from the reaction mixture.

11. A method of preparing N-(2-nitroxyalkyl) alkylnitramine which comprises: mixing about one mole of N-(Z-hydroxyalkyl) alkylamine with about 2 to about 2.2 moles of substantially anhydrous nitric acid to form a liquid reaction mixture; bringing the resulting liquid mixture into reactive relation, at a temperature between about 35 C. and about 45 C. and in the presence of a halide-ion-forming material selected from the group consisting of chlorine and bromine; with about 1.6 to about 2.3 moles of a lower fatty acid anhydride; diluting the resulting reaction mixture with water and separating the precipitated N (2 nitroxyalkyl) alkylnitramine from the mother liquor.

References Cited in the file of this patent Bamberger, Berichte Deut. Chem. GeselL, vol. 28, pp. 399. to 402, 537, 538 (1895). 

1. A METHOD OF PREPARING A NITROXYALKYL NITRAMINE FROM A SECONDARY AMINE OF THE CLASS THAT (A) CONTAINS AT LEAST ONE ALKANOL GROUP AND (B) IS CAPABLE OF DISSOLVING IN AN APPROXIMATELY EQUIVALENT AMOUNT OF SUBSTANTIALLY ANHYDROUS NITRIC ACID TO FORM A LIQUID REACTION MIXTURE, WHICH METHOD COMPRISES MIXING SAID SECONDARY AMINE WITH ABOUT AN EQUIVALENT PROPORTION OF SUBSTANTIALLY ANHYDROUS NITRIC ACID AND THEN BRINGING THE RESULTING LIQUID REACTION MIXTURE INTO REACTIVE RELATION WITH ABOUT AN EQUIVALENT PROPORTION OF A DEHYDRATING ACID ANHYDRIDE IN THE PRESENCE OF A SMALL PROPORTION OF A HALIDEION-FORMING CATALYST SELECTED FROM THE GROUP CONSISTING OF CHLORINE AND BROMINE. 